how to fix P0420 code in Honda CR-V Fifth Generation (2017-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface, and the engine is cool.
• Disconnect the negative battery terminal to avoid electrical issues.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter.
• Steps:
  1. Connect the OBD-II scanner and record live data from the oxygen sensors.
  2. Use the multimeter to test the voltage output of the upstream oxygen sensor (should fluctuate between 0.1V and 0.9V).
  3. Test the downstream oxygen sensor; it should have a more stable output.
  4. If either sensor is faulty, replace it with a new unit.

3. Inspect Catalytic Converter

• Tools Required: Wrench set, jack stands, safety goggles.
• Steps:
  1. Raise the vehicle using jack stands for better access to the exhaust system.
  2. Visually inspect the catalytic converter for any signs of physical damage or blockage.
  3. Check for any exhaust leaks that could affect oxygen sensor readings.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, gasket scraper, new gaskets, torque wrench.
• Steps:
  1. Remove the bolts securing the catalytic converter to the exhaust system.
  2. Carefully detach the catalytic converter from the exhaust system.
  3. Clean the mating surfaces on the exhaust pipe and install new gaskets.
  4. Install the new catalytic converter and tighten bolts to manufacturer specifications (typically around 25-30 lb-ft).
  5. Reconnect the oxygen sensors if they were disconnected.

5. Clear Codes and Test Drive

• Steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear any stored codes.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.